Control of the morphology of metal-ceramic microstructures by impurity addition in the model system Fe-Mn-O

Metal-ceramic multi-phase microstructures can be obtained by partial reduction of ternary or higher ceramic oxides. This subject was experimentally investigated in the model system Fe-Mn-O by reducing the oxygen partial pressure at constant temperature and total pressure. Electron microscopy studies were performed for microstructural characterization, phase identification and chemical analysis. The experimental observations are discussed based on solubility limits and the segregation of dopants. It is shown that the addition of dopants such as BaO, CaO, MgO, SrO, Al{sub 2}O{sub 3}, Cr{sub 2}O{sub 3} or ZrO{sub 2} to the initial, polycrystalline oxide solid solution (Fe{sub 1{minus}x}Mn{sub x}){sub 1{minus}{Delta}} strongly influences the location of metal precipitation during reduction.